Case report: Adult presentation of glutaric aciduria type I

Introduction - Glutaric aciduria (or glutaric acidemia) type 1 (GA1) is a rare autosomal recessive neurometabolic disorder caused by mutations in the GCDH gene that results in a deficiency of the glutaryl-CoA dehydrogenase enzyme. It plays a vital role in the degradation of L-lysine, L-hydroxylysine, and L-tryptophan. Accumulating toxic metabolites (namely glutaric acid/GA and 3-hydroxyglutaric acid/3-OH-GA) leads to progressive neurological deterioration. GA1 is one of the limited neurometabolic disorders, where we can stop the progression of the disease with a diet and aggressive emergency treatment during excessive catabolism. If undiagnosed through newborn screening, symptoms start to present in childhood between 3-36 months, with neurological symptoms related to sepsis or fever. However, 10-20% of cases start insidiously.Case report - We report the case of a 53-year-old male with GA1, who presented progressive spastic tetraparesis, dysarthria, and focal seizures. His initial symptoms, misattributed to cerebral palsy and previous ischemic strokes, had gradually worsened in recent years, leaving him bedridden. Specific metabolic laboratory testing and radiological evaluations revealed the characteristic features of the disease. Genetic testing identified a known pathogenic homozygous mutation in the GCDH gene, which confirms the diagnosis of GA1. Low-lysine diet and supplementation with carnitine and riboflavin were started. After the initiation of treatment, no further progression was observable.Conclusion - This case underscores the importance of considering hereditary neurometabolic disorders like GA1 - taking into account the available metabolic screening - not only in pediatric patients but also in adult patients with progressive neurological decline. This case contributes to the limited literature available on GA1 cases in adults and highlights the need for early detection strategies to avoid irreversible neurological damage.